Since energy issues and global environmental issues are becoming more serious, solar cells are receiving more attention as an alternative energy source for replacing fossil fuels. In the solar cell, carriers (electrons and holes) generated by photo irradiation to a photoelectric conversion section composed of a semiconductor junction or the like are extracted to an external circuit to generate electricity. Solar cell having a collecting electrode on the photoelectric conversion section is utilized for efficiently extracting carriers generated at the photoelectric conversion section to the external circuit.
Solar cells are classified broadly into thin-film-based solar cells in which a photoelectric conversion layer is deposited on a glass substrate or an electroconductive substrate, and crystalline solar cells using a single-crystalline silicon substrate or a polycrystalline silicon substrate.
Generally, a plurality of solar cells are connected in series or in parallel through a wiring member to form a module, and put into practical use. Solar cells are modularized by an appropriate method. For example, the collecting electrode of the solar cell is electrically connected to a wiring member, and adjacent solar cells are connected to each other with a gap section provided therebetween so that the solar cells are not in contact with each other. However, in a solar cell module prepared in this way, the gap section is a region which does not contribute to power generation, and therefore module power generation efficiency is insufficient.
Patent Documents 1 to 3 each propose a method for manufacturing a solar cell module in which a plurality of solar cells are stacked together with an electroconductive member interposed therebetween in such a manner that the peripheries of adjacent solar cells overlap each other. According to this method, the area of a region which does not contribute to power generation is reduced.
Patent Document 1 describes a method for manufacturing a solar cell module in which a plurality of solar cells each having a small area are connected to one another. The peripheries of solar cells are superimposed one another, and then cleaved.
Patent Document 2 describes a solar cell module in which a plurality of solar cells each including an electroconductive substrate are connected to one another using a specific electroconductive adhesive. In Patent Document 2, a thin-film-based solar cell is used in which an amorphous silicon thin-film etc. is deposited as a photoelectric conversion layer on a flexible electroconductive substrate such as a stainless steel substrate. Solar cells prepared by the above-mentioned method are cleaved to a predetermined size, and the peripheries of the solar cells are superimposed on each other. Patent Document 2 describes that the cut end surface of the solar cell is covered with an insulating material for preventing a front electrode layer and a back electrode layer being short-circuited.
Patent Document 3 describes a solar cell module in which solar cells each having a solar cell element formed on a metal foil are stacked in such a manner that the ends of the solar cells overlap one another. Patent Document 3 describes that the ends of solar cells are connected by a solder that is covered with an insulating member, so that stress concentration on the connection part can be relieved to prevent damage to the connection part, etc. Patent Document 3 describes that an amorphous silicon thin-film etc. is deposited on a metal foil to prepare a solar cell sheet, the solar cell sheet is cut to a predetermined size, and the ends of the solar cells are then superimposed on each other.